1. Field of the Invention
The present invention relates to a bearing device used for a turbocharger, for example.
2. Description of Related Art
A bearing system for a turbocharger which supports a rotational shaft that rotates at a high speed in a casing has been known, as shown in FIG. 6, which includes an cylindrical outer ring housing 91 provided in a casing 90, and rolling bearings 92, 92 mounted on respective axial sides of the outer ring housing 91 and in which the rolling bearings 92, 92 rotatably support a rotational shaft 99 positioned radially inside of the outer ring housing 91 (see Japanese Patent Application Publication No. 2010-133266 (JP 2010-133266 A)).
In the turbocharger shown in FIG. 6, an oil supply hole 96 is provided in the casing 90, and oil is supplied from the oil supply hole 96 to an outer peripheral surface 91a of the outer ring housing 91. This oil forms an oil film between an inner peripheral surface 90a of the casing 90 and the outer peripheral surface 91 a of the outer ring housing 91. Vibrations of a bearing device 97 can thus be hindered from being transmitted to the casing 90.
Further, the oil supplied to a portion between the inner peripheral surface 90a of the casing 90 and the outer peripheral surface 91a of the outer ring housing 91 is supplied into the rolling bearings 92 via portions between axial end surfaces 98 of the outer ring housing 91 and side wall surfaces 90b in the casing 90. This oil enables lubrication and cooling of the rolling bearings 92.